[Intel-gfx] [PATCH] drm/i915/selftests: Tighten the timeout testing for partial mmaps

[Matthew Auld]

On Tue, 10 Sep 2019 at 13:10, Chris Wilson <chris at chris-wilson.co.uk> wrote:
>
> Currently, if there is time remaining before the start of the loop, we
> do one full iteration over many possible different chunks within the
> object. A full loop may take 50+s (depending on speed of indirect GTT
> mmapings) and we try separately with LINEAR, X and Y -- at which point
> igt times out. If we check more frequently, we will interrupt the loop
> upon our timeout -- it is hard to argue for as this significantly reduces
> the test coverage as we dramatically reduce the runtime. In practical
> terms, the coverage we should prioritise is in using different fence
> setups, forcing verification of the tile row computations over the
> current preference of checking extracting chunks. Though the exhaustive
> search is great given an infinite timeout, to improve our current
> coverage, we also add a randomised smoketest of partial mmaps. So let's
> do both, add a randomised smoketest of partial tiling chunks and the
> exhaustive (though time limited) search for failures.
>
> Even in adding another subtest, we should shave 100s off BAT! (With,
> hopefully, no loss in coverage, at least over multiple runs.)
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Matthew Auld <matthew.auld at intel.com>
Reviewed-by: Matthew Auld <matthew.auld at intel.com>